1. Field of the Invention
The present invention relates to an apparatus for recording or forming desired image information on a photosensitive medium.
2. Discussion of the Prior Art
Image recording systems as shown in FIGS. 4 and 5 are known in the art of recording images on a photosensitive medium.
In the recording system of FIG. 4, an exposing device 1 is used to irradiate an original 4 which bears an image to be reproduced. A radiation produced by a light source 2 of the exposing device 1 is converged on the surface of the original 4, by suitable means such as a reflector 3, and is reflected by the surface of the original 4. The reflected radiation passes through suitable optical focusing means such as a lens array 5, and is focused on the surface of a photosensitive paper 6, which is exposed to the reflected radiation, whereby a latent image corresponding to the image on the original 4 is formed on the exposed photosensitive paper 6. The exposure of the photosensitive paper 6 to the reflected radiation takes place while the paper 6 is fed from a supply roll 7 along a predetermined feed path, toward a developing device 8. In the present illustrated system, the exposed portion of the photosensitive paper 6 is sensitive to a pressure, and the development of the latent image is effected by passing the exposed photosensitive paper 6 through a nip of pressure rollers of the developing device 8. Thus, the latent image optically formed on the photosensitive paper 6 is developed into a visible image corresponding to the image on the original 4.
The recording system of FIG. 5 employs an exposing device in the form of a laser scanner device 9. This scanner device 9 includes a semiconductor laser element 10 for emitting a laser which is eventually incident upon the photosensitive paper 6, by way of a polygon mirror 12 rotated by a drive motor 11, an f-.theta. lens 13, and a reflector mirror 14. The laser element 10 is operated according to image signals from an external device. Thus, a latent image represented by the image signals is formed on the photosensitive paper 6. The latent image is developed by the developing device 8.
However, the known image recording systems of FIGS. 4 and 5 suffer from the following drawbacks:
In the system of FIG. 4, only a portion of the radiation produced by the light source 2 reaches the surface of the photosensitive paper 6. Therefore, if the sensitivity of the paper 6 is relatively low, the system requires the light source 2 to have a relatively large capacity, to assure a sufficient intensity of the radiation. Further, the photosensitive paper 6 should be fed at a relatively low rate. In the system of FIG. 5, the intensity of the laser emitted from the laser scanner device 9 is generally not high enough to sufficiently expose the photosensitive paper 6. Hence, the photosensitive paper 6 cannot be fed at a high speed, unless the sensitivity of the paper 6 is considerably high.
In an attempt to solve the above drawbacks, an image recording apparatus as shown in FIG. 6 has been proposed. This apparatus uses a xerography unit 15 which includes a photosensitive drum 16, an electrostatic charger 17, a first exposing device 18, a first developing device 19, a cleaning device 20 and a discharger 21. The photosensitive drum 16 has an outer circumferential surface to which a toner is applied by the first developing device 19, whereby a visible light-shielding image is formed on the surface of the drum 16. The thus formed visible light-shielding image is transferred to a rotating transparent endless film 22 made of an electrically insulating material. The transferred light-shielding image on the endless film 22 is used as a photomasking pattern through which the photosensitive paper 6 is exposed by a second exposing device 23. Thus, the latent image corresponding to the photomasking pattern is formed on the photosensitive paper 6, and is subsequently developed by the second developing device 8 as used in the recording systems of FIGS. 4 and 5. The toner forming the light-shielding image or photomasking pattern is removed from the transparent endless film 22 by a cleaning device 24, so that the cleaned length is again used for the next image reproduction cycle.
In the image recording apparatus shown in FIG. 6, a considerable portion of the radiation produced by the second exposing device 23 can be effectively utilized to expose the photosensitive paper 6. Consequently, the paper 6 can be fed at a comparatively high rate, even where the sensitivity of the paper 6 is relatively low.
However, the recording apparatus of FIG. 6 also suffers from some drawbacks. Namely, a variation in the thickness of the endless film 22, a poor contact of the endless film with the photosensitive paper 6, an entry of dust between the film and paper 22, 6, may cause unsatisfactory sharpness of the latent image formed on the paper 6, since the paper 6 is exposed to the radiation through the photomasking pattern on the endless film 22. Further, the present known apparatus requires a complicated mechanism for feeding both the endless film 22 and the photosensitive paper 6, which increases the frequency of maintenance service of the apparatus as a whole.